Rule of thumb...I aim for all voltages in a cathode follower to be a third each of the B+. My schematic I commonly use.

.....in concertina I don't bother with split cathode resistor.
solong it's DC bias strapped to preceeding stage which is in control. I've always assumed since the stage operates with fantastic neg feedback, the concertina distortion is already extremely low or an be ignored if Correctly operated..